Hi, Amy!
At Disney's Saratoga Springs Resort & Spa, the Congress Park area sits right along the lake which separates the resort from Downtown Disney. Instead of walking out the front of any building here, toward the parking spaces, the sidewalks to the main pool and the bus stop, head out the other side where you'll find a path that follows the edge of the lake. This path curves around to the right and brings Guests right to the sidewalk that adjoins the bus stop at The Marketplace. The first store on your left will be Disney's Days of Christmas, with Disney Design-a-Tee on your right.
Take a look at this
map of Saratoga Springs Resort & Spa, where you'll see the buildings labeled "F" in red, toward the bottom right corner are Congress Park. That lake you see on the map is one side of the same lake you can see in this
map of Downtown Disney, Village Lake. At Downtown Disney, you cannot catch a bus to a theme park, though. However, if you'd rather not walk back to Saratoga Springs Resort, you can simply hop on a resort bus at DD to SS, then hop off at the first resort stop and wait for the next bus to the park of your choice. If you're heading to Magic Kingdom from DD, just hop onto a bus for Disney's Contemporary Resort and either take the walking path to MK or the monorail.
You're going to love your stay! Send more questions as you think of them, Amy. I love to help! :-)